Floating vent for railway tank car safety relieve valve

ABSTRACT

A railway tank car for the transport of liquids has a safety relief valve which is actuated at a predetermined pressure. A float on the outer end of a flexible conduit which communicates with the relief valve permits the flexible conduit to be exposed to gases in the void volume of the tank even when the tank is overturned and the safety valve is on the bottom of the tank shell instead of the top of the tank shell. Excessive gaseous pressures in the tank shell which might occur upon derailments with the tank shell tilted or overturned is communicated or vented directly to the safety relief valve by the end of the flexible conduit which is exposed to the void volume of the tank shell.

United States Patent Kunz et al.

[451 Mar. 21, 1972 [72] Inventors: Eugene L. Kunz, Florissant; Ronald P.

Bolte, St. Louis, both of Mo.

[73] Assignee: ACF Industries, Incorporated, New York,

[22] Filed: Nov. 25, 1970 [2]] Appl.No.: 92,575

FOREIGN PATENTS OR APPLICATIONS 6,839 4/1895 Great Britain ..137/578 Primary ExaminerI-lenry T. Klinksiek Attorney-Eugene N. Riddle [57] ABSTRACT A railway tank car for the transport of liquids has a safety relief valve which is actuated at a predetermined pressure. A float on the outer end of a flexible conduit which communicates with the relief valve permits the flexible conduit to be exposed to gases in the void volume of the tank even when the tank is overturned and the safety valve is on the bottom of the tank shell instead of the top of the tank shell. Excessive gaseous pressures in the tank shell which might occur upon derailments with the tank shell tilted or overturned is communicated or vented directly to the safety relief valve by the end of the flexible conduit which is exposed to the void volume of the tank shell.

4 Claims, 6 Drawing Figures FLOATING VENT FOR RAILWAY TANK CAR SAFETY RELIEVE VALVE BACKGROUND OF THE INVENTION Railway tank cars for the transport of liquid ladings normally have safety relief valves mounted adjacent the upper portion of the tank shell in a dome structure. The relief valves are exposed to the void volume of the tank shell above the liquid lading when the tank cars are in transit on the tracks. However, upon accidents, such as derailments, with the tank tilting or overturning, the safety valve sometimes is not in direct communication with the void volume of the tank shell in which excessive gaseous pressure may be reached.

DESCRIPTION OF THE INVENTION A railway tank car for the transport of liquid lading has an outer shell of a generally cylindrical cross section and a safety relief valve is mounted within the upper portion of the tank shell for actuation at a predetermined pressure for venting to atmosphere. A generally rigid casing extends generally vertically downwardly from the valve inwardly of the tank shell to a position in the general area of the center of the tank shell, and a flexible hose-like conduit is connected to the lower end of the rigid casing for relative rotative movement. The flexible conduit or member has a length at least equal to the radius of the tank shell and a float member is mounted on its outer end adapted to float on the upper surface of the liquid lading to communicate the outer end of the flexible member with any gaseous fluid within the void volume in the tank shell. Thus, upon the overturning of the tank shell the float member seeks the upper horizontal surface of the liquid lading to expose the safety valve directly to the gaseous volume in the shell.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

FIG. 1 is a partial side elevation, with certain parts broken away, of a railway tank car having dome structure and safety relief valve comprising the present invention;

FIG. 2 is an enlarged section of the safety relief valve shown in Fig. l and illustrating the swivel connection for the flexible conduit;

FIG. 3 is a schematic indicating various positions of the flexible conduit upon various levels in the liquid lading being transported by the railway tank car;

FIG. 4 is a schematic indicating the position of the flexible conduit upon a tilting of the tank in a longitudinal direction;

FIG. 5 is a generally schematic end view showing the flexible conduit in its normal position with the railway tank car filled with a liquid lading; and

FIG. 6 is a generally schematic end view similar to Fig. 5 but showing the tank in an overturned relation with the flexible conduit in communication with the void volume in the tank.

Referring now to the drawings for a better understanding of this invention, a railway tank shell 10 ofa railway tank car is shown having a dome structure generally indicated 12 mounted thereon. Dome structure 12 includes a housing 14 secured to the tank shell 10 and a cover 16 mounted for pivotal movement at 18 on housing 14. A safety valve vent 20 is provided in dome cover 16. A safety relief valve is mounted within dome structure 12 and is generally indicated at 22. Safety valve 22 comprises an upper casing 24 and a main valve body 26 having valve 28 mounted therein. A lower valve stem 30 has a spring seat 32 on its lower end secured thereon by nut 34. A compression spring 36 is compressed between spring seat 32 and valve body 26 as shown in Fig. 2. An upper stem 40 of valve 28 extends through an opening in an upper retainer 42 which is mounted over valve body 26 and retained thereon by nut 44. An O-ring 46 is mounted between the upper end of valve 28 and retainer 42.

Valve body 26 is secured by mounting flange 48 and studs 50 having nuts 52 threaded thereon to hold valve body 26 against tank shell 10. Lower casing 54 has a mounting flange 56 secured by studs 58 to shell 10. A suitable seal 60 is provided between mounting flange 56 and tank shell I0.

Lower casing 54 extends vertically downward to a position generally at the center of tank shell 10 and has a threaded lower end 62. A connecting sleeve 64 is threaded on lower end 62 and an elbow 66 is received within sleeve 64. Ball bearings 68 permit elbow 66 to swivel relative to outer sleeve 64. An additional connecting sleeve 70 receives the other end of elbow 66 and ball bearings 72 permit relative rotative movement between connecting sleeve 70 and elbow 66. A short pipe extension 74 is mounted within the threaded end of connecting sleeve 70 and a flexible hose-like conduit 76 is secured over extension 74. Flexible conduit 76 is of a length greater than the radius of tank shell 10 and may be substantially longer depending on the length of the tank and the diameter of tank shell 10. Mounted about the extending free end of flexible hose or conduit 76 is a float 78 which has a buoyancy adequate to float on the upper surface S of the liquid lading.

Thus, as shown in the drawings, the upper end of flexible conduit 76 is exposed directly to the void volume within tank shell 10 formed between tank shell 10 and the upper surface S of the liquid lading thereby to communicate safety relief valve 22 directly with any gases or gaseous pressure within tank shell 10. Upon the overturning of the tank shell 10 such as shown in Fig. 6, float 78 will seek the upper surface S of the liquid lading and thus, safety relief valve 22 will remain in direct communication with any gaseous volume within tank shell 10. Likewise, upon tilting or shifting of tank shell 10, the free end of conduit 76 will seek the upper surface S of the liquid lading.

Safety relief valve 22 is a conventional safety relief valve and upon the gaseous pressure rising to a predetermined level, retainer 42 will unseat from O-ring 46 to relieve such excessive pressure. Upon a drop in the pressure to the predetermined level, retainer 42 will reseat on gasket or O-ring 46 to prevent any further drop in volume. The spring tension in spring 36 may be adjusted by nut 34.

It is desirable to communicate the gaseous pressure directly with the safety relief valve since the gaseous pressure is relieved or reduced rapidly upon an opening of the safety relief valve. It the safety relief valve is exposed only to the liquid lading, the relief valve would open at the predetermined pressure but the reduction of pressure would be relatively slow as liquid discharge from the safety valve is substantially slower than a gaseous discharge. Thus, the internal pressure within the tank car might remain extremely high for a long period of time if the relief valve is only exposed to the liquid lading and only liquid lading is vented to the atmosphere by the safety valve. The present invention permits a rapid decrease in pressure even upon tilting or overturning of the tank shell since the gaseous volume communicates directly with the safety relief valve.

What is claimed is:

1. In a railway tank car having a tank shell adapted to transport liquid lading, a safety relief valve mounted adjacent the upper portion of the tank shell and being actuated at a predetermined pressure for venting to atmosphere, a generally rigid casing extending generally vertically downwardly from said valve inwardly of the tank shell, a flexible hose-like member secured to the rigid casing, and a float member adjacent the outer end of the flexible member adapted to float on the upper surface of the liquid lading to communicate the outer end of the flexible member with any gaseous fluid within the void volume in the tank shell.

2. In a railway tank car having an outer tank shell of a generally cylindrical cross section adapted to transport liquid lading, a safety relief valve mounted adjacent the upper portion of the tank shell and being actuated at a predetermined pressure for venting to atmosphere, a generally rigid casing extending generally vertically downwardly from said valve inwardly of the tank shell to a position in the general area of the center of the tank shell, a flexible hose-like member secured tive rotative movement between the flexible member and rigid casing.

4. In a railway tank car as set forth in claim 3, said means connecting the flexible member to the rigid casing comprising an elbow mounted for rotative movement relative to said rigid casing and relative to said flexible member.

@ 3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,650,293 Dated March 21 1972 Inventor) Eugene L. Ku nz and Ronald P. Bolte It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' The title should' read "Floating Vent For Railway Tank Car Safety Relief Valve". Y

Column 3, line 5, after "length" insert at least signed and sealed this 17th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. In a railway tank car having a tank shell adapted to transport liquid lading, a safety relief valve mounted adjacent the upper portion of the tank shell and being actuated at a predetermined pressure for venting to atmosphere, a generally rigid casing extending generally vertically downwardly from said valve inwardly of the tank shell, a flexible hose-like member secured to the rigid casing, and a float member adjacent the outer end of the flexible member adapted to float on the upper surface of the liquid lading to communicate the outer end of the flexible member with any gaseous fluid within the void volume in the tank shell.
 2. In a railway tank car having an outer tank shell of a generally cylindrical cross section adapted to transport liquid lading, a safety relief valve mounted adjacent the upper portion of the tank shell and being actuated at a predetermined pressure for venting to atmosphere, a generally rigid casing extending generally vertically downwardly from said valve inwardly of the tank shell to a position in the general area of the center of the tank shell, a flexible hose-like member secured to the lower end of the rigid casing, and a float on the outer end of the flexible member adapted to float on the upper surface of the liquid lading to communicate the outer end of the flexible member with any gaseous fluid within the void volume in the tank shell, the flexible member being of a length equal to the radius of the tank shell.
 3. In a railway tank car as set forth in claim 2, means connecting the flexible member to the rigid casing permitting relative rotative movement between the flexible member and rigid casing.
 4. In a railway tank car as set forth in claim 3, said means connecting the flexible member to the rigid casing comprising an elbow mounted for rotative movement relative to said rigid casing and relative to said flexible member. 